The present invention relates in general to devices for filtering silt and debris from water flows, and in particular to a device that fits over the open end of a storm water drainage system outlet so as to collect and filter silt and other storm debris from runoff water flowing through storm water drainage pipes.
In the construction of new housing and other types of developments, the road system generally is first marked out and the streets into and through the development are cut and graded. Thereafter, the storm water drainage system for the development is constructed, which typically includes the underground drainage pipes, collection boxes and culverts, and drop inlets that form the manholes or drain openings along the street, and outlet pipes for discharging the runoff water. During such construction and thereafter, however, dirt, silt and debris are typically washed into and collected within the collection boxes and discharge pipes of the storm water drainage system. Since these storm water drainage systems almost always dump the water, and thus, the debris carried therewith into a stream, lake, river or other water source, it is necessary and desirable to clean this water flow of as much debris and silt as possible because of potential environmental hazards to fish, animals and humans from such a build-up of dirt and debris and the potential clogging of the drainage pipes due to such build-up.
Trying to periodically clean the silt and debris from a storm sewer drainage pipes is, however, a difficult operation and generally is not very effective as heavy rainstorms and cleaning/washing of the street during construction not only washes more silt and debris into the drainage pipes, but the silt and debris collected within the storm sewer drainage pipes typically will be washed along and out of the pipes with this run-off or cleaning water. In addition, these cleaning efforts at times will simply involve hosing or spraying the dirt or debris out of the pipes.
Storm water drainage filters have been developed for filtering run-off water to remove sand and debris therefrom to prevent the collection of such dirt and debris within the storm water drainage system pipes. For example, see my U.S. Pat. No. 5,843,306 discloses a silt guard system for blocking the passage of silt and debris from being washed into a storm water inlet while still enabling runoff water to drain easily therethrough. In addition, U.S. Pat. Nos. 5,297,367, 5,744,048, 5,643,445, 5,587,072, 5,575,925 and 4,268,390 further disclose storm drain screens or outlet filters for filtering or trapping debris being carried into a storm sewer. These conventional filter devices, however, typically require a filtering structure that is mounted over or within a storm sewer and often includes a removable filter which must be frequently removed for cleaning or replacement after collection of dirt and debris therein.
Accordingly, it can be seen that a need exists for a device for filtering runoff water from a storm water drainage system of silt and other debris, which addresses these and other problems in the art.
Briefly described, the present invention generally comprises a filter assembly for filtering silt and debris for run-off water discharged from a outlet pipe of a storm water drainage system. The filtering assembly mounts to the outlet or discharge end of the storm sewer outlet pipe, enclosing the discharge end of the outlet pipe. As a result, the water flow being discharged from the outlet pipe of the storm sewer is discharged through the filter assembly whereupon it is substantially filtered and cleaned of silt, dirt and other debris to prevent this silt, dirt and other debris from being carried with the water flow into nearby streams, rivers, lakes, etc.
The filter assembly generally includes a filter bag having a bag body formed from a filtering material. The filter bag body includes an open proximal or first end and a closed distal or second end and upper and lower bag walls that define an inner bag chamber in which a silt, debris, etc. is collected or trapped. Flaps in the upper surface or wall of the bag body enable excess run-off water to drain therefrom as the bag becomes filled with collected silt and debris. A collar member, typically having a cylindrical or rectangular configuration so as to mate with or engage the inner wall of the outlet pipe of the storm water drainage system, is as attached to the proximal or first end of the filter bag for connecting the filter bag to the outlet pipe.
The collar member generally is formed from one or two pieces, defining a pair of opposed sections and generally is made of a metal material. The collar member includes a sidewall adapted to engage and bear against the inner wall of the outlet pipe to secure the collar member in place within the outlet pipe. The collar member further includes upstream and downstream ends with the upstream end being received within the outlet pipe and with the first end of the filter bag being received over and secured to the downstream end of the collar member. A rim is formed at the downstream end, with the rim typically comprising an annular flange that projects radially from the sidewall of the collar member. The rim can be substantially flat or also can be curled over toward the sidewall of the collar member. The rim provides a bearing surface against which the proximal or first end of the filter bag is secured using a cable tie, adhesive, hooks or other similar fastening mechanism so as to prevent the filter bag from being dislodged from the collar member as the water flow passes therethrough and as silt and debris is collected and builds up within the inner chamber of the bag. An expansion assembly also is mounted within the collar member between the opposed sections. The expansion assembly can be adjusted to urge the sections together or apart as needed to fit the outlet pipe so that the sidewall of the collar member is urged into tight engaging contact with the inner sidewall of the outlet pipe.
In use, the collar member is fitted within the outlet pipe and its expansion assembly adjusted so as to urge the sidewall of the collar member into tight engaging contact with the inner wall of the outlet pipe. The filter bag is then applied over and is secured to the downstream end of the collar member with the open or proximal end of the outlet bag being secured against the rim of the collar member. Thereafter, as runoff water flows through the storm water drainage system and out of the outlet pipe, it is discharged through the filter bag, which collects and traps dirt, silt and other debris while the water flow passes through the filtering material of the filter bag so as to substantially clean the water flow of silt, dirt and other debris. Once the filter bag has been filled with collected debris and dirt, the filter bag can be removed and its open proximal end sealed. The filter bag can either then be left in place with a new filter bag being installed on top of the filled filter bag, or can removed and used as a retaining support, or openings can be formed in the top of the filter bag and vegetation planted therein to help in erosion control around the discharge end of the outlet pipe.
Various objects, features and advantages of the present invention will become apparent to those skilled in the art upon a review of the following specification, when taken in conjunction with the accompanying drawings.